Various inspections and diagnostics are employed to monitor wear and tear on an engine. With respect to metallic components within an engine (for example, engine bearings, the aft sump pump, and the gearbox), wear and tear may manifest as the flaking off of metallic debris into an oil subsystem used for lubricating the engine. Therefore, evaluating the oil associated with an engine is one diagnostic approach employed in engine health monitoring systems.
In some approaches to evaluating engine oil, a metallic chip detector collects ferrous metals from scavenged engine oil returned to the oil tank; in this approach the metallic chip detector may include magnets. In other approaches, a metallic chip detector evaluates the scavenged oil for both ferrous and nonferrous metallic debris by determining, for each object of metallic debris, a measure of initial impedance across a gap, as the measure of impedance provides conductivity information. In these approaches, when an object of metallic debris is detected, it is often “zapped” with a high energy electrical charge that is intended to burn/eliminate the metallic debris. This procedure is referred to as “chip zap.” Often, a number of repetitions of zapping may be employed in effort to eliminate each object of metallic debris detected, and this number, along with the initial impedance of the metallic debris, is recorded as chip zap data into a summary report.
The summary reports are often stored and evaluated later. When the summary reports are associated with a turbofan engine of an aircraft, the evaluation of the summary report generally occurs as part of an engine health maintenance review at a ground station. A number of zaps in a summary report has been utilized to postulate that the engine has experienced enough wear and tear that it should be removed and replaced. However, subsequent engine analysis has indicated that this measure of wear and tear is somewhat inefficient, in that it results in removing and replacing more engines than necessary (often referred to as resulting in too many false positives). As is readily appreciated, replacement of an engine is costly and time consuming.
Therefore, an improved system and method for identifying engine wear based on engine oil debris is desirable. The desirable system and method utilize chip zap data provided in summary reports, and process, for each object of metallic debris, an initial (pre-zap) impedance and an impedance change (post zap) with respect to configurable reference variables. The desirable system and method generate alerts (suggesting potential engine wear) responsive to the impedance values of the objects of metallic debris and the reference variables. The provided system and method realize these improvements. Furthermore, other desirable features and characteristics of the exemplary embodiments will become apparent from the subsequent detailed description.